This invention relates to a slitting-scoring machine for traveling webs of corrugated cardboard which are ultimately formed into cardboard boxes. A representative machine of this type is disclosed in European Patent Publication No. 0 078 429 published on Oct. 15, 1982. Such machines usually include at least one scoring section for scoring longitudinal lines in the web, and at least one slitting section for appropriately longitudinally slitting the web so that it may ultimately be folded into box shape. Each section includes upper and lower scoring or slitting blades, as the case may be, which engage the web in an opposed manner for performing the desired function. In each section, a plurality of upper blades are arrayed in adjustably spaced relationship transversely across the web, with the lower blades being similarly arrayed.
Heretofore, most blades were mounted on very large solid rotatable shafts, with each blade being formed of a plurality of segments mounted around the outside of the shaft. It has been observed that this known construction had certain disadvantages in that the rotating shafts tended to deflect due to separating forces between tooling pairs. The preset distance between upper and lower opposed blades thereupon undesirably changed so that the scoring lines on the web were either too deep or shallow, and the cut ended up being ragged. There was no way to control this problem in the known construction.
In addition, in many prior known devices the blades on each shaft were adjusted therealong by a single external robot, which only moved one blade at a time into its desired position. In view of the fact that many scoring and cutting blades might be disposed on a given shaft, moving each blade individually on a given shaft resulted in an undesirably large amount of time being consumed to adjust all the blades on a single shaft.
Futhermore, the scoring and cutting blades in some prior devices known to the inventors were individually and separately locked to their respective shafts. This, also, was time consuming as well as being of costly construction.
The caliper or gap between opposed scoring blades is of substantial importance so that the score lines on the traveling web are of the correct thickness, as mentioned above. Adjustment of the caliper in known prior devices was also difficult, and tended to adversely affect slitting blade overlap.
It is an object of the present invention to essentially solve the aforementioned combination of problems occurring in the known prior slitting-scoring machines.
In accordance with the various aspects of the present invention, the machine frame mounts a pair of upper and lower girder-like box beams of heavy construction. The upper box beam is provided with a mounting means from which is suspended a plurality of upstream upper scoring assemblies and a plurality of downsteam upper slitting assemblies. The upper face of the lower box beam is also provided with a mounting means which supports a plurality of upstream lower scoring assemblies and a plurality of downstream lower slitting assemblies. The series of assemblies include circumferentially integral slitting or scoring blades, as the case may be, which are mounted for rotation with rotatably driven shafts of smaller diameter.
The box beams extend transversely of the traveling web, and each box beam is provided with upstream and downstream ways extending therealong which support the plurality of slitting-scoring assemblies. Besides the blades, the assemblies include a motor connected to be driven along its beam, and an encoder, with all of the motors and encoders being electrically connected to a programmable computer or the like. The computer may be pre-programmed with the desired position and spacing of all the assemblies, so that upon the push of a single button to create a single input signal all of the motors simultaneously drive all of the assemblies to their desired position.
Each of the slitting-scoring assemblies also carries a bearing block which is engageable by an elongated cam rod extending along the beam. There is a cam rod for each array of assemblies, and rotation of a rod causes simultaneous locking of all assemblies in its array in position along the beam.
The important function of adjusting the caliper or gap between opposing scoring blades is accomplished in the present embodiment by mounting the upper box beam so that it is pivotable upwardly about the rotatably driven shaft for the upper slitting assembly blades, which are downstream of the scoring blades. An actuator is suitably controlled to pivot the upper beam, which thereby raises or lowers the upper scoring blades relative to the fixed lower scoring blades. By adjusting the caliper of the scoring blades independently of the slitting blade overlap, the overlap may be kept at a minimum, which increases slitting blade life and improves slit quality.
Temperature gradients within the device may undesirably affect the dimensional stability of the machine. This is especially true of the box beams and the mounting and drive connections for the slitting-scoring assemblies. Any change in length or shape of these elements could cause the actual spacing of the assemblies to vary from the desire spacing. The problem is essentially solved by internally stabilizing the temperature of the box beams. In the present embodiment, the beams are sealed and thermostatically controlled fluid passes therethrough.